Diabetic foot ulcer (DFU) is a serious complication of diabetes and hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. The evidence supporting the use of HBOT in DFU treatment is controversial. The aim of this work was to introduce a DFU model in ZDF rat by creating a wound on the back of an animal and to investigate the effect of HBOT on the defect by macroscopic evaluation, quantitative histological evaluation of collagen (types I and III), evaluation of angiogenesis and determination of interleukin 6 (IL6) levels in the plasma. The study included 10 rats in the control group (CONT) and 10 in the HBOT group, who underwent HBOT in standard clinical regimen. Histological evaluation was performed on the 18th day after induction of defect. The results show that HBOT did not affect the macroscopic size of the defect nor IL6 plasma levels. A volume fraction of type I collagen was slightly increased by HBOT without reaching statistical significance (1.35±0.49 and 1.94±0.67 %, CONT and HBOT, respectively). In contrast, the collagen type III volume fraction was ~120 % higher in HBOT wounds (1.41±0.81 %) than in CONT ones (0.63±0.37 %; p=0.046). In addition, the ratio of the volume fraction of both collagens in the wound ((I+III)w) to the volume fraction of both collagens in the adjacent healthy skin ((I+III)h) was ~65 % higher in rats subjected to HBOT (8.9±3.07 vs. 5.38±1.86 %, HBOT and CONT, respectively; p=0.028). Vessels density (number per 1 mm2 ) was found to be higher in CONT vs. HBOT (206.5±41.8 and 124±28.2, respectively, p<0.001). Our study suggests that HBOT promotes collagen III formation and decreases the number of newly formed vessels at the early phases of healing., Jiří Růžička, Martina Grajciarová, Lucie Vištejnová, Pavel Klein, Filip Tichánek, Zbyněk Tonar, Jiří Dejmek, Jiří Beneš, Lukáš Bolek, Robert Bajgar, Jitka Kuncová., and Obsahuje bibliografii